Abstract: Addition crosslinkable organopolysiloxane compositions which cure to organopolysiloxane elastomers of high elongation at break and high tear resistance contain a high viscosity, alkenyl-terminated, and substantially pendant alkenyl group-free organopolysiloxane, an organopolysiloxane having pendant alkenyl groups and optionally alkenyl-terminal groups, an Si—H functional crosslinker, and a hydrosilylation catalyst.

Abstract: Linear-chain copolysiloxanes comprising units of the general formulae (1) and (2),

Abstract: The silicone compositions, in particular silicone oils and crosslinkable silicone compositions, contain porphyrins as heat stabilizer.

Abstract: Organopolysiloxane compositions which are stabilized to heat and can be crosslinked to give elastomers, which as stabilizer combination contain (D) a copper compound in an amount from 1 to 180 ppm by weight calculated as elemental copper and (E) a zinc compound in an amount of from 1 to 180 ppm by weight calculated as elemental zinc, in each case based on the total weight of the organopolysiloxane composition which is stabilized to heat and can be crosslinked to give elastomers, and (F) optionally, organic fatty acid.

Abstract: A process for preparing organopolysiloxanes having SiC-bonded organofunctional groups, which comprises reacting an organopolysiloxane containing SiC-bonded hydroxyl and/or alkoxy groups and having an average of about 0.85 to 1.8 SiC-bonded monovalent hydrocarbon radicals or halogenated monovalent hydrocarbon radicals for each Si atom, with an organosilicon compound containing alkoxy groups and/or siloxane oxygen groups and at least one SiC-bonded organofunctional radical per molecule in the presence of an organic solvent and a basic catalyst.The resultant organopolysiloxanes having SiC-bonded organofunctional groups may, for example, be used for preparing modified polymers by copolymerizing the organopolysiloxanes with a monomer containing an aliphatic double bond, such as styrene or hydroxyethyl methacrylate, or by reacting the organopolysiloxanes with an additional polymer such as an epoxy resin.

Abstract: A process for preparing organosiloxane block copolymers which comprises reacting (a) an organopolysiloxane containing Si-bonded hydroxyl groups and having an average molecular weight of at least 800 g/mole, in which at least 80 mole percent of the units are siloxane units, and one valence of each silicon atom is satisfied by an SiC-bonded organic radical, while the remaining silicon valences are satisfied by siloxane oxygen atoms or hydroxyl groups, with (b) a diorganopolysiloxane having one Si-bonded hydroxyl group in each terminal unit and an average of at least 10 silicon atoms per molecule in the presence of (c) an organic solvent and (d) an alkali metal carbonate and/or an alkali metal carboxylate to form an organosiloxane block copolymer.

Abstract: The present invention relates to an improved process for increasing the molecular weight of silicon compounds and more particularly to an improved process for increasing the molecular weight of silicon compounds containing Si-bonded alkoxy groups.